Tank for aircraft



Nov. ll, 1941.

G. w. HARDMAN TANK FOR AIRCRAFT Filed June 26, 1939 3 Sheets-Sheet 1 INVENTOR- Wffardma/z ATTORNEY George Nov. 11, 1941. G. w. HARDMAN TANK FOR AIRCRAFT Filed June 26, 1939 3 Sheets-Sheet 2 INVENTUL .deorgeKHardmanf By ATTORNE Patented Nov. 11, 1941 TANK Fon. AIRCRAFT George W. Hardman, Brookline, Pa., assignor to Edward G. Budd Manufacturing Co., Philadelphia, Pa., a corporation of Pennsylvania Application June 26, 1939, serial No. 281,679

1 Claim.

The present invention relates to aircraft, and more particularly to a combined tank and frame structure for airplane wings.

Airplane wings, particularly of the cantilever type usually have an airfoil contour having considerable thickness, and affording considerable space between the top and bottom skin sheets which may be advantageously employed for fuel storage tanks. The internal structure of the wing, necessary to give the cantilever structure thereof strength, considerably honeycombs the space inside, heretofore precluding the use of large tanks because of interference with structural members. Such internal structure may consist of a plurality of airfoil contoured rib trusses lying in spaced vertical planes extending fore and aft, and a shear web member, or members, extending spanwise in a vertical plane. In one form of wing structure, the leading edge and top and bottom skin structures together with a single shear web form a torsion box of elongated D cross-section which box contains spaced parallel truss members or ribs. The forward half of the wing comprising the torsion box is the principal load carrying portion of the wing and it is therefore most desirablel to position fuel tanks in this space, but with the closely spaced rib truss members traversing this space, tanks of any size have heretofore been precluded, unless the trusses themselveshave been weakened or repositioned in less advantageous-positions insofar as strength of wing is concerned.

The present invention is adapted to utilize the space between the upper and lower surface at the forward portion of airplane wings for relatively large storage tanks adapted to contain fuel, water, or the like, and is adapted to accomplish this without weakening the wing construction, and without necessitating the use of a large number of relatively small separate tanks separated from one another by trusses cutting thru the space. This is accomplished by providing a plurality of struts within a tank, and aligning the struts within the tank with the truss structure so that the struts may be rigidly secured to the truss structure and become a part thereof, as well as combine with the baille structure of the tank.

Accordingly. an object of the invention is to provide a tank structure of considerable size for use-in an aircraft wing and in which4 the tank structure itself forms a part of the truss structure of the wing.

Another object of the invention is to provide a tank struct-ure for an aircraft wing in which a tank is adapted to intersect one or more rib internal baille plates of the tank structure cooperate with the truss structure of the wing to increase the strength thereof.

A further object of the invention is to provide a tank structure for an aircraft wing in which members of the wing, and inwhich the tank structure has a reinforced baille adapted to lie in the plane of each rib member so intersected and in which the strength of each baille structure is adapted to cooperate with each rib member so intersected so as to impart sufficient strength to such rib member.

Still another object of the invention is to provide a tank structure for aircraft wings in which the tank structure intersects and forms a structural part of one or more rib members and in which the ta structure is adapted to be readily withdrawn an disassembled from the rib structures and the wing structure without injury thereto and in which substitute tanks may be inserted, readily without any substantial complication.

The above and other novel features of the invention will appear more fully hereinafter from the following detailed description when taken in conjunction with the accompanying drawings. It is expressly understood, however, that the drawings are employed for purposes of illustration only and are not designed as a definition of portion of the tank and the wing taken on the line 3-3 of Fig. 2;

Fig. 4 is an enlarged detail of the upper central portion of Fig. 2 with parts broken away.; Fig. 5 is a section taken on the line 5-5 of Fig- 4;, Fig. 6 is a section line 6-6 of Fig- 4; Fig. '7 is an enlarged sectional detail view of taken substantially on the the forward upper portion of Fig. 2 with portions lbroken away;

Fig. 8 is'a still further enlarged section of Fig. 7 taken substantially on the line 8 8;

'dicated in Fig. 1.

is located within theV wing structure.

Fig. 9 'is an enlarged detail view'of the lewe rear portion of Fig. 2; and

22, the same being separable from the fuselage portion Yon the line 24 as is well understood in 'the art since, for practical reasons, wing structures are made in separable sections; The tip portion may be of the D spar .typeV such as will appear clear from Fig. 2, although the longitudinally extending shear web 26 is invisibly in- Referring to Fig. 2, the D' spar'will be seen to have top and bottom reinforced skin surfaces 28 and 38 having corrugated backing metal 32 for stiiening and reinforcing purposes. 'I'he top and bottom skins 28 and 30 are joined together at the nose through Aa. tip plate 34 whichis stiffened by Z members 36 and 38. As is illustrated also in Fig. 1, a plurality of ribs 40,42, 41,46, 4a, su, sz, 54, 5s, etc., are provided, extending transverse to the shear web 26 in korder to give the wing ysurfaces the proper -airfoil contour and for providing the necessary strength.

In wing structures of this type, the rib structuresgenerally are composed of a pair of spaced chord'members each having the proper curvamation. As illustrated in Fig. 2 and Fig. 3, such chord members appear as 58 and 60. In order to emciently distribute the load and weight in an airplane, the various heavy parts thereof are often distributed along the wingso thattheir load may be directly carried thereby. For example, in Fig. 1, an engine nacelle 62 is shown located part way out the wing structure, thereby more directly loading the wing structure. Tile supply of fuel also constitutes a heavy load which has heretofore been located, to considerable extent, within the wing structllre and, as is illus-v trated in Fig. 1, a fuel tank such as 64 according to a main feature of the present invention y As has previously been set forth, theA honeycombing of the bracing requiredwithin the wing structure .r

has-required the use of a series of small tanks filling such spaces as occur. In some instances,

spaces free from braces and other structure have been purposely enlarged in order that a larger.

tank might be accommodated;` and this has been done to the detriment of the strength of the Whole structure. 1.

It will appear in Fig. 1 that the tank 64 is armembers, were it not for the intersecting tank. In a tank of the size illustrated, it is necessary to employ a considerable number of spaced bailles in order to prevent the surging of the liquid within the tank during rough weather and -maneuvers, and a feature of the present invention contemplates the aligning of these baille plates within the planes of the ribs intersected by the tank. As shown in Fig. 3, the chords 58 and 60 may be those of any of the rib members 40 through sz,- nd are aligned with hanles es ar:

ranged within the tank itself. The tank itselfis siderable strength in tension, and by employing members may also have strength incompression, the same may combine together with stilening members to form the bracing structure required by each rib where intersected by the tank. Thus, as is illustrated'in Fig. 2, the baille plate 66 is provided with stiifening flange channel members, arranged in the form of diagonals 14 and 16, and a vertical strut 18. As is illustrated in Fig. 6, the vertical strut 18 is composed of a pair of flanged channels arranged with their base portions 88 in back-to-back relation and against the baille plate 66, or the baille plate and such gussets 82 and 83 as may be employed adjacent the end of the strut for strengthening purposes. Ihe base portions 8l) of the channel members forming the strut 18 are spot welded together through the baille plate 66A at frequent intervals along its 'length so that all members form in eect an integral column.

Diagonals 14 and 'I8 are also composed of anged channel members but are arranged on opposite sides of thebaiiles with their flanged portionsv 84 in contact with the baille or such gusset plates as are arranged near the extremity to strengthen the baule. Likewise, a `series of spot welds secure the anges of the opposite channels forming the members 16 and 'I4 through the intervening baille 66 and such gusset plates as 82 and 83 as will be required, the spot welds *ranged in such a Way as to' intersect a number of being arranged along the length thereof to lform an integral structllre between the members.

In order to transmit the stresses of the strut 18 and the brace member 14 through the skin of the tank and to the chord member 58, a stress trans-l fer member 86 is employed having a cylindrical portion 88 and a fiat shank portion 80, the cylilk drical portion also being provided with a disc ange 92. Through an aperture 94 in the tank skin 68, the cylindrical portion of the stress transfer member extends, and the iiange 92 thereof is seam welded to the tank skin in :duid-tight manner as is illustrated at 98. The shank portion of the stress member is aligned With and extends along one side of the strut 18 and lies within the channel thereof and is spotwelded to the strut at a plurality of points 'as is indicated at |00. Thus, the shank portion is rigidly secured to the strut 18, the gussets 82, the bailie plate 66, and thus has a rigid connection to the upper end of the diagonal 14. Additionally, the flange of the stress member has a rigid connection to the tank skin 66, and through the angle members 10 has a rigid connection to the gusset plates- 82 through the spot welds, for example, |02.

The end of the stress transfer member may be provided with a threaded aperture |04 adapted to receive a' bolt I 06 passing through the base of The adjacent ends of the strut 18 and the brace 16 are secured in a substantially identical manner to thatheretofore described with relation to the adjacent ends of the strut 1 8 and members 14.

Since itis desirable that the liqlld Within the tank f aaeaeoe be permittedto flow freely from one end to the other of the tank at a lowpoint in the tank, the gusset members may be cut away, as at |06, so as to provide a space for fuel to flow from one side of the baille to the other. The metal, instead of being cut away, may form a flange such as to stiften the gusset and such other flanges, such as H2, may likewise be used for stiffening purposes. The individual baille plates may also have large apertures therein such'as I4 which will be preferably flanged to assist in stii'lening the baille plate.

The brace members 16 and 14 at their ends, that is the forward, upward corner or the lower, rear corner, are adapted to transmit their stresses through the tank as is illustrated more particularly in Figs. 7 and 8 and Figs. 9 and 1'0. Referring particularly to Figs. '1 and 8, the brace member 16, composed of fianged channel members on opposite sides of the baille 66, are secured with their flanges 85 secured to one another through the bafile 66 through the many spot welds I I6 l0- cated along the length thereof. At the end, gusset plates |20 on both sides of the baille 66, are provided between the channel members, and at the tip end, the stresses from the baille plate 66, channel members 16 and gusset plates |20 are transmitted to the angle strip 10 and thence to the skin of the tank 68. On the outside of the v'tank at this point, are positioned a strengthening plate |22 together -with spaced parallel facing angle strips |24 and |26 between the facing angles of which is arranged a channel member |28 having a face |30 adapted to be Secured to the chord member 58 through the threaded fastening means |32. The angle strip 10, reinforcing strip |22, angle pieces |24 and |26, as well as the channel member |28 are all secured `together by a sexies of spot welds substantially as shown and the stresses from the brace 16 are transmitted through the chord member 50 through the fastening means |32, the latter lying substantially in line with the brace.

The brace member 14 (see Figs. 9-10) terminates in a manner similar to that of 16, there being providedgusset plates '|34 on either side of the baille plate 66 and squeezed between the flanges 84 of the channels of the brace member 1d. Again the stress is transmitted through the skin of the tank through the angle member 10 to a reinforcing plate |36, spaced parallel fastening angle members |38|40 and a channel member |42 having a face |44 thereof adapted to be secured to -a complementary channel member |46 secured to ashear web and rib. The members |42 and |46 may be -stiiened as shown at |43 and |41. The channel member4 |42 is provided with outwardly extending flanges |48 and |50 along the edges of its side walls, which nanges are spot welded to nat plates |52 and |54 extending tangentially into engagement with the tank at |56 and |58. As before, except for tle threaded fastening means |60 all the parts are preferably spot welded at frequent intervals in order to secure the parts in proper relation-ship. The upper right hand corner of the tank is provided with a similar fastening means to' the lower corner of the tank, with the exception that the gussets |34 are not present for 'the reason that no brace members such as ,14 extend to this corner and the parts therefore, are otherwise identical to those in the lower right hand corner. i

The complementary channel member |46 embraces the chord member 60 and is spot welded thereto as at |62. The channel member is also provided with flanges |64 which are similarly welded to the flanges 6| of the chord member 60.

The channel attaching member |46 closely embraces the flanged channel member |66 extending vertically across the shear web 26 and is secured to -the shear web through laterally extending flanges |68 on the attaching channel and the flanges |69 of the shear web channel |66 to which the flanges |68 are welded. The bolts |10 extending through the flanges of the flanged channel member |66 and the fastening .channel member |46 extend through'the shear web to an opposing flanged channel member |12 as is illustrated in Figs. 2 and 9.

Since for repairs and replacements it may even be desirable to remove the tank from the wing, the tank has a generally tapered, gradually reduced cross section as it extends outward into the wing, and by removing the fastening means |60, |10, and |32, at each of the ribs, it is possible to slide the tank lengthwise of the wing out through its root and when that section of the wing is detached from the remainder of the wing as on the line of separation 24. To remove the fastening means or to reinsert the same upon assembly of the wing and `tank, access holes |80 are provided, the details ofV which are illustrated in both Figs/l and 5 as well as 7 and 8. Referring to Fig. 4, it will be seen that the skin sheet 28 is provided with a round aperture |82 and an annular flange |84 around the rim thereof and on the inside surface of the slnn. Also, the corrugated backing metal 32 is cut away as at |86 so that free accessv to the bolt |06 is afforded through the use of any well known socket wrench. To cover the hole, a disc cover plate |88 adapted to closely :dll the aperture |82 and to seat upon the flange |84 is provided and to hold the same in place, a transverse bridge member |60 is provided adapted to engage notches |92 in the depending portion |96 of the ange |64, and by drawing the screw and nut |86 between the bridge and the disc |83, the aperture is securely closed in a smooth workman-like manner, It will readily appear that the bridge member when loose upon the screw may be inserted through the hole eccentrically and thereafter correctly positioned and drawn up tight as described. Such apertures are provided as is shown in Fig. 7 and Fig. 8 for the fastening means |32 and are also provided in conjunction with the fastening means |60 the same being arranged to the rear of the shear web and connection being obtained therefrom through apertures |98 in the vertical channel member |66 and an aperture 200 in the shear web 26, it being understood that through the use of a universal type of socket wrench, the fastening means may be readily inserted through such a line-up of apertures. It will be understood also that where the threaded fastening means includes a nut, the same will be secured in place by welding, for example, as is illustrated, in connection' with the nut 202 and Y its weld connection 204 to the channel member |42.

From the foregoing description, it will appear that thev tank, constructed as described, is readily insertable in the spaces provided for it in the rib structures of awing and that upon insertion of the tank into such space, and the insertion and tightening of such fastening means as are provided for, the tank and its baille plates and associated struts and braces cooperate with the chords of the rib structure so as to provide as strong a rib structure as would be possible i f ribinthe same were the tank not present. Further, it will appear that the baile plates are considerably stilfened by the presence of the struts and` braces, and that the braces and struts cooperateV with the baille plates to the end that both may be made lighter and both readily assist in performance of the other's function. While no particular end structure of the tank has been described, sinceV in normal usage the end of tank wouldnot be aligned with a rib structure, yet if desired, it will readily appear that the tank end structure could be associated with as aluminum alloys andthe like might be used,

if desired, one of the principal features of the invention being the design of a tank removable fromthe wing structure and yet having the cooperation between its baille structure, the wing rib struchxre, such as hereinabove described.

Although a single embodiment of the inventionhasbeenillustratedanddescribeditisto be understood that the invention is not limited altered to suit stress conditions. since such changes in construction vand arrangement of` partsAmay 'be made aswell as others, without departing from' the spirit of the invention. as will belwell understood by those skilled in the art, reference will be had to the appended claim for a denitionof theA limits of the invention.

What is claimed is:

In an airplane wing, a yplurality of ribs, top

and bottom skins covering said ribs, each of said ribs having top and bottom chord members, a fuel tank within said wing disposed between said chord membe a plurality of reinforcing truss structures within said tank, each' of said truss structures being disposed substantially in the vertical plane of a rib and including a vertical strut, said strut having top and botthereto,butmaybeembodiedinvariousme-V chanieal forms and arrangements. For example,

the arrangement of struts and braces may be tom ends extending through said tank and terminating in attaching faces in direct engagement with adjacent faces of the respective top. and bottom chord members, said faces being disposed in planes extending longitudinally of the wing and transverseLv of the vertical planes of said struts, said 4top and bottom skins having openings therethrough in alignment with the refspective ends of said struts, and cap screws in- 'sertable through said openings for rigidly securing said engaged faces together, the axes of said cap screws being disposed in vertical planesv substantially parallel to the vertical planes of said struts. Y

GEORGE W. HARDMAR 

